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Biomedical subjects

Yasuhiro Honda

Publications and source records attributed to Yasuhiro Honda.

At least 37 records · Page 2Linked to original sources
PubMed2004

Six- and twelve-month results from first human experience using everolimus-eluting stents with bioabsorbable polymer.

BACKGROUND: Everolimus, an active immunosuppressive and antiproliferative agent of the same family as sirolimus (rapamycin), has demonstrated significant reduction of neointimal proliferation in animal studies. The First Use To Underscore restenosis Reduction with Everolimus (FUTURE) I trial was the first in-human experience to evaluate the safety and efficacy of everolimus-eluting stents (EES), coated with a bioabsorbable polymer, compared with bare metal stents (BMS). METHODS AND RESULTS: FUTURE I was a prospective, single-blind, randomized trial that enrolled 42 patients with de novo coronary lesions (EES 27, BMS 15). Patient and lesion characteristics were comparable between the groups. Major adverse cardiac event rates were low at 30 days and 6 months, without any early or late stent thrombosis for either group (P=NS). Between 6 and 12 months, there were no additional reports of major adverse cardiac events. The 6-month angiographic in-stent restenosis rate was 0% versus 9.1% (1 patient) (P=NS), with an associated late loss of 0.11 mm versus 0.85 mm (P<0.001), and the in-segment restenosis rate was 4% (1 patient) and 9.1% (1 patient) (P=NS) for EES and BMS, respectively. Intravascular ultrasound analysis revealed a significant reduction of percent neointimal volume in EES compared with BMS (2.9+/-1.9 mm3/mm versus 22.4+/-9.4 mm3/mm, P<0.001). There was no late stent malapposition in either group. The safety and efficacy of the EES appeared to be sustained at 12 months. CONCLUSIONS: In this initial clinical experience, EES with bioabsorbable polymer demonstrated a safe and efficacious method to reduce in-stent neointimal hyperplasia and restenosis.

Aged↗
PubMed2004

Validation of a thermographic guidewire for endoluminal mapping of atherosclerotic disease: an in vitro study.

Temperature heterogeneity along the inner surface of an artery may be a surrogate marker of impending plaque rupture and has been associated with an increased likelihood of future coronary events. Initial studies using catheter-based thermographic devices have demonstrated that the changes in temperature are subtle, while the effects of coronary flow on measured temperature have not yet been examined. A novel guidewire-based system (ThermoCoil, Imetrx) designed to measure surface temperature in coronary arteries was used to study the effects of heat source intensity and flow on measured temperature. An in vitro model of a focal, eccentric, heat-generating lesion demonstrated that a guidewire-based system can detect changes in surface temperature with a precision of less than 0.08 degrees C. In this model, temperature measurements increased linearly with source temperature and decreased with increases in flow by an exponent of -0.33 (P < 0.001 for both). Flow rates and heat source properties can significantly influence the measurement and interpretation of thermographic data. The incorporation of 2D thermographic images may contribute further to the characterization of metabolically active plaques likely to cause acute coronary syndromes.

Artificial Intelligence↗
PubMed2003

Late incomplete stent apposition and focal vessel expansion after bare metal stenting.

Late incomplete stent apposition was observed in 2.4% of the 412 stented segments studied by serial intravascular ultrasound analyses. Most of these phenomena and all late vessel expansions with incomplete stent apposition developed in vessels in which lesions were treated by atherectomy before stenting, suggesting a potential association between mechanical injury from debulking and these phenomena.

Aged↗
PubMed2003

Coronary vasodilation by noninvasive transcutaneous ultrasound: an in vivo canine study.

OBJECTIVES: We evaluated the coronary vasodilatory effects of transcutaneous low-frequency (27-kHz) ultrasound (USD). BACKGROUND: Ultrasound has been shown to affect vascular function. METHODS: Ultrasound energy was administered transcutaneously to 12 dogs. Coronary arterial dimensions were assessed using intravascular coronary ultrasound (IVUS) and quantitative coronary angiography (QCA). RESULTS: The IVUS mid-left anterior descending (LAD) luminal area was 6.77 +/- 1.27 mm(2) at baseline. After 30 s of ultrasound, this area increased by 9% (7.40 +/- 1.44 mm(2), p < 0.05), after 3 min by 19% (8.05 +/- 1.72 mm(2), p < 0.05) and after 5 min increased by 21% (8.16 +/- 1.29 mm(2), p < 0.05). The mean coronary diameter (2.69 +/- 0.33 mm) at baseline (QCA of three segments of LAD and three segments of left circumflex coronary artery) increased by 19.3% (3.21 +/- 0.28 mm) after 5 min of USD exposure. After a 90-min observation period there was a return to baseline values (p = NS). Intracoronary nitroglycerin (NTG) administered to five dogs revealed a similar magnitude of vasodilation as USD. CONCLUSIONS: Noninvasive, transthoracic low-frequency USD energy results in coronary artery vasodilation within seconds of exposure. The vasodilation is reversible and is similar in magnitude to that induced by NTG. Further evaluation is needed to assess its potential applications in humans.

Administration, Cutaneous↗
PubMed2003

Noninvasive transcutaneous ultrasound augments thrombolysis in the left circumflex coronary artery--an in vivo canine study.

BACKGROUND: Ultrasound has the potential to augment chemical thrombolysis. METHODS AND RESULTS: Thrombotic occlusions in the left circumflex artery (LCx) were induced in 27 dogs. Sixty minutes later, tissue-type plasminogen activator (t-PA) was given intravenously over 90 min. Thrombotic occlusions (n = 20) were treated with concomitant transcutaneous low frequency (27 kHz), continuous wave (CW) (n = 10) or pulsed wave (PW) (n = 10) ultrasound. Tissue-type plasminogen activator plus ultrasound (n = 20) vs. tissue-type plasminogen activator alone (n=7) resulted in more frequent Thrombolysis in Myocardial Infarction (TIMI) 3 flow (90% vs. 43%, P = 0.024) and less reocclusion (11% vs. 67%, P = 0.080). At 60 min, median TIMI grade flow for tissue-type plasminogen activator alone was 2 (mean: 1.43 +/- 1.40) compared to 3 (mean: 2.70 +/- 0.95) for tissue-type plasminogen activator plus continuous as well as pulsed wave ultrasound (P = 0.035). Continuous wave and pulsed wave ultrasound were equally effective in augmenting thrombolysis. Histologically, no ultrasound-mediated injury to the myocardium or coronary arteries occurred. CONCLUSION: Both transcutaneous low frequency continuous wave ultrasound and pulsed wave ultrasound enhance tissue-type plasminogen activator-mediated thrombolysis of the posterior circulation with higher TIMI 3 flow rates and less reocclusion than with tissue-type plasminogen activator alone. In addition, at the energy levels used, low frequency ultrasound appears safe.

Animals↗
PubMed2003

Impact of deep vessel wall injury on acute response and remodeling of coronary artery segments after cutting balloon angioplasty.

Deep vessel wall injury is believed to affect vessel dimension following coronary intervention. The cutting balloon is designed to treat coronary artery stenoses with dilatation and surgical incisions, thereby reducing excess vessel injury. This study examines the effect of deep vessel wall injury on acute and late coronary arterial response after cutting balloon angioplasty. Serial volumetric intravascular ultrasound (IVUS) analyses were performed in 63 lesions treated with cutting balloon angioplasty alone. Before intervention, the longitudinal range of the lesion segment that included the smallest lumen area (LA) was determined as LA <4 mm(2) and/or LA stenosis >60%. The exact corresponding site at postintervention and follow-up was aligned using peri- and intravascular landmarks. Average vessel area (VA), plaque area (PA), and LA were measured. Lesion segments were categorized as with or without deep vessel wall injury, which was defined as the presence of plaque/vessel wall fracture extending to the sonolucent (medial) layer. Before intervention, the lesion vessel size of deep injury group was smaller than that of the nondeep injury group (p <0.05 for average VA and PA), whereas average lesion LA, lesion length, and reference vessel size did not differ. Immediately after cutting balloon angioplasty, the deep injury group showed a significant increase in VA (p <0.0001) and a lesser decrease in PA (p <0.01) compared with the nondeep injury group. During follow-up, the increase of VA tended to be greater in the deep injury group than in the nondeep injury group (p = 0.06), whereas the change of PA did not differ. Consequently, LA decrease was less in the deep injury group than in the nondeep injury group (p <0.05). From these results, it is suggested that deep vessel wall injury tends to occur in lesions with relatively small size and such lesions show favorable vessel response after cutting balloon angioplasty.

Aged↗
PubMed2003

Relationship between neointimal regrowth and mechanism of acute lumen gain during the treatment of in-stent restenosis with or without supplementary intravascular radiation.

We investigated whether neointimal regrowth is related to the mechanism of acute lumen gain during the treatment of in-stent restenosis (ISR) lesions both with and without adjunct intravascular brachytherapy. From the WRIST (Washington Radiation for In-Stent Restenosis Trial) cohort, 54 ISR patients ((192)Ir, 29; placebo, 25) were treated with nonrepeat stenting percutaneous interventions (excimer laser, rotational atherectomy, and/or balloon angioplasty) prior to (192)Ir or placebo therapy. Using Simpson's method, serial volumetric intravascular ultrasound (IVUS) analyses (pre- and posttreatment and 6-month follow-up) were analyzed to obtain stent, lumen, and intimal hyperplasia (IH) volumes that were then adjusted for stent length to create stent, lumen, and IH volume indexes. In the placebo group, the acute reduction of neointima (1.6 +/- 1.4 mm(3)/mm) was counteracted by intimal regrowth (2.1 +/- 1.7 mm(3)/mm). The amount of intimal regrowth correlated directly with the intimal reduction due to the intervention (r = 0.76; P < 0.001), but not with the amount of additional stent expansion. In the (192)Ir-treated group, intimal regrowth was significantly less than in the placebo group (-0.3 +/- 0.1 vs. 2.1 +/- 1.7 mm(3)/mm; P < 0.001) despite a similar initial intimal reduction (1.3 +/- 0.9 vs. 1.6 +/- 1.4 mm(3)/mm; P = NS). No correlation was found between intimal reduction at the time of the procedure and intimal regrowth in the (192)Ir group. In this study, neointimal regrowth following treatment of ISR lesions correlates directly with the extent of acute intimal volume reduction, but not with the extent of additional stent expansion. This relation is not seen in ISR segments treated with radiation, where intimal regrowth is substantially inhibited.

Aged↗
PubMed2003

Taxol-based eluting stents from theory to human validation: clinical and intravascular ultrasound observations.

Treatment with antiproliferative drugs via coated stents appears to be a promising approach to both mechanically remodel target lesions and biologically reduce neointimal hyperplasia. Drug-eluting stents can maximize local drug effects and minimize the potential for systemic toxic effects. The purpose of this review is to describe the effects of a lipophilic microtubular inhibitor, paclitaxel, a strong antiproliferative agent under clinical investigation, and to define the vascular response to taxol-based eluting stents by intravascular ultrasound.

Angiogenesis Inhibitors↗
PubMed2002

Delivered dose and vascular response after beta-radiation for in-stent restenosis: retrospective dosimetry and volumetric intravascular ultrasound analysis.

BACKGROUND: Observations from previous intracoronary radiation therapy trials noted a considerable discrepancy between the prescribed radiation dose and the dose actually delivered. The aims of this study were to investigate the effect of actual delivered dose on vascular changes and to test the appropriateness of the current dose prescription. METHODS AND RESULTS: Serial volumetric intravascular ultrasound (IVUS) analysis was performed in 30 in-stent restenosis cases treated with a 40-mm (90)Sr/Y source train. The fixed dose was prescribed at 2 mm from the centerline of the source train (18.4 Gy at 2 mm for reference diameter < or =3.35 mm and 23 Gy for diameter > or =3.36 mm). Only stent segments with full radiation coverage and device injury were enrolled and divided into 2-mm-long subsegments (n=202). D(S90)EEM (the minimum dose absorbed by 90% of the external elastic membrane surface) was calculated as the delivered dose corresponding to each segment, assuming that the radiation catheter occupied the same position in the vessel as the IVUS catheter. Mean D(S90)EEM of 23.5+/-5.82 Gy (range 12.3 to 41.7 Gy) was delivered to these subsegments. Overall, intimal hyperplasia volume remained constant from postintervention to follow-up (2.23+/-1.10 to 2.32+/-1.09 mm3/m; P=NS). Regression analysis revealed there was no correlation between delivered dose intensity and changes in intimal hyperplasia volume. No particular dose-dependent complications were appreciated in this delivered dose range. CONCLUSIONS: The current dose-prescription protocol of (90)Sr/Y radiation to native in-stent restenosis lesions may provide substantial inhibition of neointimal reproliferation regardless of the actual delivered dose intensity.

Beta Particles↗
PubMed2002

7-hexanoyltaxol-eluting stent for prevention of neointimal growth: an intravascular ultrasound analysis from the Study to COmpare REstenosis rate between QueST and QuaDS-QP2 (SCORE).

BACKGROUND: Inhibition of neointimal tissue growth has been demonstrated in preliminary human feasibility studies with a stent-based polymer sleeve delivering 7-hexanoyltaxol. The Study to COmpare REstenosis rate between QueST and QuaDS-QP2 (SCORE) trial is a human, randomized, multicenter trial comparing 7-hexanoyltaxol (QP2)-eluting stents (qDES) with bare metal stents (BMS) in the treatment of de novo coronary lesions. The purpose of this substudy was to evaluate the acute expansion property and long-term neointimal responses of qDES compared with BMS as assessed by intravascular ultrasound (IVUS). METHODS AND RESULTS: A total of 122 (qDES 66, BMS 56) patients were enrolled into the IVUS substudy. All IVUS images (immediately after the procedure and at 6-month follow-up) were analyzed at an independent core laboratory in a blind manner. At baseline, qDES achieved stent expansion similar to BMS. At follow-up, qDES showed reduced neointimal growth by 70% at the tightest cross section and by 68% over the stented segment (P<0.0001 for both), resulting in a significantly larger lumen in qDES than in BMS. Unlike intracoronary brachytherapy, there was no evidence of negative edge effects, unhealed dissections, or late stent-vessel wall malapposition over the stented and adjacent references segments in either group. CONCLUSIONS: Detailed IVUS analysis revealed that qDES had comparable acute mechanical and superior long-term biological effects to BMS. Although the long-term benefits and limitations of this technology require further investigation, the reduction in neointimal thickenings demonstrated that local delivery of 7-hexanoyltaxol through polymer sleeves augments conventional mechanical treatment of atherosclerotic disease.

Blood Vessel Prosthesis Implantation↗
PubMed2002

Late vascular response to repeat stenting for in-stent restenosis with and without radiation: an intravascular ultrasound volumetric analysis.

BACKGROUND: Re-stenting of in-stent restenosis (ISR) improves acute angiographic results. Methods and Results- Volumetric intravascular ultrasound analysis was performed in 70 ISR lesions that received either placebo (n=36) or (192)Ir radiation (n=34). ISR lesions treated by re-stenting were divided into 3 groups: old stent not re-stented (A), old/new stent overlap (B), and new stent only (C). ISR lesions treated without re-stenting were categorized as D. In placebo patients, postintervention lumen volume index (LVI) was significantly greater in re-stented segments B and C than in non-re-stented segment A (P<0.05).At follow-up, however, LVI was similar in all 4 segments secondary to the increased intimal hyperplasia (IH) reaccumulation within the re-stented segments. In patients treated with (192)Ir radiation, LVI was maintained from baseline to follow-up only in non-re-stented segments A and D. Conversely, there was a significant decrease in LVI in re-stented segments B and C (P<0.05). Qualitatively, 79% of patients in the irradiated group had stent struts with undetectable neointimal versus only 27% in the placebo group (P<0.001). Coefficient of variation of IH reaccumulation was greater in re-stented segments of (192)Ir patients (B=57.3% and C=58.9%) than in re-stented segments in placebo patients (B=27.3% and C 26.8%) and non-re-stented segments in irradiated patients. CONCLUSIONS: Additional lumen gain from re-stenting ISR lesions is counteracted by exaggerated neointimal proliferation in placebo patients. Maximum effectiveness and safety of radiation can be achieved for ISR lesions when treated without re-stenting. Thus, regardless of supplementary intravascular brachytherapy, repeat stenting strategies provided little long-term advantage.

Blood Vessel Prosthesis Implantation↗